A system may include one or more serial interfaces for the transmission or reception of serial data. An interface may be a clock data recovery (CDR) based interface that recovers a clock signal from data, including, for example, a (Serializer-Deserializer) interface providing serialization and deserialization of data for transfer.
A serial interface may utilize a significant amount of power because of the CDR circuit itself and because of the reference oscillator, such as a frequency multiplier PLL, that is generally used when high frequencies are necessary. To order to reduce power consumption, a conventional system may switch off the interface in certain circumstances.
However, the startup latency of the CDR and reference oscillator components may be unacceptable and may waste power during the startup period. In low power modes for devices, it is common to run circuitry at lower frequencies, but such a low power mode does not result in significant power savings when using a CDR component in an interface.